DE69822151T2 - EPOXIDATION METHOD USING A HETEROGENIC CATALYST COMPOSITION - Google Patents

Description

Gebet the invention

These The invention relates to an improved epoxidation process in which a titanium-containing catalyst composition is used. The Catalyst composition is prepared by liquid phase impregnation a silicon-containing solid with a titanium halide such as titanium tetrachloride in a hydrocarbon solvent and subsequent Calcining produced. If necessary, the catalyst is also with Water and / or reacted with a silylating agent. The catalyst performance is improved by allowing the calcination at high temperature (preferably at least 700 ° C) essentially without oxygen.

background the invention

It There are already many different processes for producing epoxides been developed. Such a process involves epoxidation an olefin in a liquid phase reaction using an organic hydroperoxide as the oxidizing agent and certain solubilized metal compounds as a catalyst. earlier Studies in this area came to the conclusion that optimal epoxidation rates and selectivities for epoxy generally be achieved by being in an organic reaction medium soluble Metal catalysts used.

One clear disadvantage of an epoxidation process in which a soluble metal compound used as a catalyst is the difficult recovery the catalyst for reuse in later runs. If the other components of an epoxidation reaction mixture (typically Epoxide, unreacted olefin, solvent, unreacted Hydroperoxide and the alcohol derived from the reacted hydroperoxide) relatively volatile are, can these components by distillation of the soluble, non-volatile Catalyst separated and the catalyst in the form of a bottom stream recovered become. However, a problem with this method is that The bottom stream may tend to contain certain heavy substances like acids and polymers accumulate, resulting in reuse of the stream adversely affect the epoxide selectivity or olefin conversion can. The catalyst may also tend to precipitate out of solution, when the bottom stream is overly concentrated becomes. Therefore, it may be necessary to do a relatively extensive job Bottom flow attributed to what the productivity of the epoxidation process. That's why it would be special desirable, an insoluble (heterogeneous) To develop epoxidation catalyst, which has high activity and selectivity and by Filtration or similar Separation techniques readily recovered from a Epoxidationsgemisch or in the form of a fixed bed and the like can be used.

US-A-4,367,342 discloses an olefin epoxidation process in which an olefin in Presence of an insoluble Catalyst of an inorganic oxygen compound of titanium is contacted with an organic hydroperoxide. Such Catalysts are disclosed in GB-1,332,527 and US-A-4,021,454, 3,829,392 and US Pat 3,923,843 closer described. Unfortunately, as described in these publications Catalysts produced no optimal activity and selectivity. Also the incorporation of relatively high amounts of titanium in catalysts of this Type to the catalyst activity It was not easy to improve.

consequently would it be maximum he wishes, alternative methods for the synthesis of heterogeneous titanium-containing catalysts to develop the shortcomings Do not have the method of the prior art, but reliably and practically materials with higher activity and selectivity in olefin epoxidation reactors.

GB-1 332 527 teaches a process for preparing an improved silica-titania catalyst by impregnating an inorganic siliceous solid with a substantially non-aqueous solution of a titanium compound in an oxygen-substituted hydrocarbon solvent, removing the solvent from the impregnated silicon-containing solid and the subsequent calcination of the impregnated silicon-containing solid is characterized. Suitable solvents for this purpose are limited to oxa and / or oxo substituted hydrocarbons which are liquid at ambient conditions and generally comprise from 1 to 12 carbon atoms. Such solvents include alcohols, ketones, ethers and esters. According to this patent, there is the reason why silica-titania catalysts produced by a process using an oxygen-substituted hydrocarbon impregnation solvent have improved properties as compared with similar catalysts prepared by other processes that one Catalyst has a more uniform content of titanium dioxide, which is not agglomerated.

A later filed patent application ( EP 0 345 856 ) discloses the preparation of epoxidation catalysts allegedly more active than the analogous catalysts obtained by previously known methods. EP 0 345 856 teaches the impregnation of silica with a gaseous stream of titanium tetrachloride followed by calcination, hydrolysis and optionally silylation. In a comparative example, a catalyst made by impregnating silica with a solution of tetraisopropyl orthotitanate complexed with acetylacetone in isopropanol solvent proved to be 4.5 times less active than the catalyst prepared by vapor phase impregnation with titanium tetrachloride , It can be seen from this disclosure that it is not possible to achieve similar catalytic activity while maintaining high epoxide selectivity when using a liquid phase instead of a vapor phase impregnation process.

EP 0 734 764 teaches an improvement of the liquid phase impregnation process disclosed in GB 1 323 527, in which the catalyst is washed after impregnation of silica with a solution of a titanium compound in an oxygen-containing organic solvent and removal of the impregnation solvent with a wash solvent and then calcined. Preferably, the washing solvent is an alcohol. It is taught that the scrubbing prior to calcination is necessary to obtain a catalyst that has both excellent activity and selectivity, although testing of the in EP 0 734 764 The examples given show that with this method, in fact, only a very modest improvement in catalyst performance is achieved. Another practical disadvantage of this method is that large amounts of solvent waste are generated, which must either be disposed of or cleaned and recycled. Such disposal or purification will substantially increase the manufacturing cost of the catalyst. Yet another drawback is that it is difficult to incorporate large quantities of titanium since significant amounts of titanium are removed during washing. This effect is even more pronounced when using large amounts of the titanium reagent with respect to the silica. Moreover, this method does not allow accurate control of the final titanium content of the catalyst.

We have now found an effective, practical method of preparing catalyst compositions having epoxidation activity and selectivity similar to those of the catalysts described in U.S. Pat EP 0 345 856 obtained by the skilled artisans are at least comparable.

Summary the invention

• (a) Imprägnieren eines organischen siliciumhaltigen Feststoffs mit einer Lösung eines Titanhalogenids in einem nicht oxidierten Kohlenwasserstofflösungsmittel, um einen imprägnierten siliciumhaltigen Feststoff herzustellen;
• (b) Calcinieren des imprägnierten siliciumhaltigen Feststoffs

wobei das Verfahren durch die wesentliche Ausschließung von Wasser, bis zumindest Schritt (a) vollendet ist, gekennzeichnet ist.The invention provides an olefin epoxidation process wherein the catalyst composition used therein is obtained by a process comprising the steps of:

• (a) impregnating an organic silicon-containing solid with a solution of a titanium halide in an unoxidized hydrocarbon solvent to produce an impregnated silicon-containing solid;
• (b) calcining the impregnated silicon-containing solid

the process being characterized by the substantial exclusion of water until at least step (a) is completed.

Possibly For example, the process for preparing the catalyst includes the additional ones Steps of heating of the catalyst in the presence of water (which at the same time as the Calcination can take place) and / or the treatment of the catalyst with a silylating agent. The epoxidation activity of the catalyst can be significantly improved by taking the calcination step at relatively high temperature (e.g., 500 to 1000 ° C) substantially without oxygen performs. The harmful ones However, effects of the presence of oxygen during calcination may occur be caught by using a reducing gas such as carbon monoxide in the calcination atmosphere initiates.

detailed Description of the invention

The epoxidation process of the invention uses a titanium-containing heterogeneous catalyst prepared by a specific process. As it has unexpectedly been found, this method can produce materials that provide better epoxidation results than materials made by other liquid phase impregnation processes. The manufacturing method of the catalyst is characterized by impregnating an inorganic silicon-containing solid with a titanium halide solution in a non-oxidized hydrocarbon solvent. For this purpose suitable solvents are those hydrocarbons which contain no oxygen atoms, are liquid at ambient temperatures and can solubilize the titanium halide. Generally speaking, it is desirable to choose hydrocarbon solvents that can achieve titanium halide concentrations of at least 0.5% by weight at 25 ° C. The hydrocarbon solvent should preferably be relatively volatile so that it can readily be removed from the inorganic siliceous solid after impregnation. Therefore, solvents having normal boiling points of 25 to 150 ° C can be used with good results. Particularly preferred classes of hydrocarbons include, but are not limited to, C ₅ -C ₁₂ aliphatic hydrocarbons (straight chain, branched or cyclic), C ₆ -C ₁₂ aromatic hydrocarbons (including alkyl substituted aromatic hydrocarbons), halogenated C ₁ -C ₁₀ aliphatic hydrocarbons and halogenated aromatic C ₆ -C ₁₀ hydrocarbons. Most preferably, the solvent does not contain any elements other than carbon, hydrogen and (optionally) halogen. When halogen is in the solvent, it is preferably chloride.

On Wish can also used mixtures of unoxidized hydrocarbons become. Preferably, this is used for impregnation purposes solvent essentially free of water (i.e. anhydrous). It can indeed also oxygen-containing hydrocarbons such as alcohols, ethers, esters, Ketones and the like in admixture with the necessary, not oxidized hydrocarbon, but in a desirable embodiment the invention is during of impregnation only unoxidized hydrocarbon present. Examples of suitable Hydrocarbon solvent include n-pentane, n-hexane, n-heptane, n-octane, n-nonane, n-decane, neohexane, cyclohexane, cyclopentane, 2-methylbutane, methylpentanes, methylcyclohexane, dimethylpentanes, Methylhexanes, dimethylhexanes, methylheptanes, trimethylpentanes, benzene, Toluene, xylenes, cumene, ethylbenzene, t-butylbenzene, methylene chloride, Chloroform, carbon tetrachloride, ethyl chloride, dichloroethanes, Tetrachloroethanes, chlorobenzene, dichlorobenzenes, trichlorobenzenes, Benzyl chloride, chlorotoluenes and the like and their isomers.

in the In contrast to that described in Example 1 of US-A-4,021,454 Process in which water is added to a mixture of titanium tetrachloride and silica is added in n-heptane is the method of the invention in preferred embodiments characterized in that water is substantially excluded at least, at least until the impregnation is completed (i.e., after removal of the impregnating solvent), and preferably until after calcination. For the purposes of this invention, "substantially excluded" means that water does not intentionally added or initiated or, if so, before the introduction of titanium halide is removed (because this to tends to react with water and the desired interaction of the titanium halide with the surface of the inorganic siliceous solid interferes). The use of reagents and starting materials containing water in the trace amounts which normally and mostly sold in such a trade Substances are present, is within the scope of the invention. Preferably are less than 500 ppm of water in the unoxidized hydrocarbon (stronger preferably less than 100 ppm of water). As follows described in detail, it is particularly desirable to use the inorganic to dry the silicon-containing solid before use.

suitable Titanium halides include titanium compounds having at least one Halogen substituent, preferably chloride, attached to the titanium atom is. Although that for the use of the most preferred titanium halide titanium tetrachloride Examples of other titanium halides useful in the impregnation step include Titanium tetrafluoride, titanium tetrabromide, titanium tetraiodide, titanium trichloride and the mixed halides of Ti (III) or Ti (IV). Next to the Halide can also other substituents such as alkoxide or amino groups present be. Preferably, however, all substituents attached to the titanium are halide.

The Concentration of the titanium halide in the hydrocarbon solvent While not critical, it is typically within the range from 0.01 to 1.0 mol / 1. The concentration of titanium halide in Hydrocarbon solvent and the amount of solution used is preferably adjusted so that in the finished catalyst Titanium content of 0.01 to 10 wt .-% (calculated as Ti based on the total weight of the catalyst) is provided. The optimal Titanium content is influenced by several factors. In general applies: the larger the surface of the inorganic siliceous solid, the larger the Amount of titanium, which without loss of activity (measured at a constant Ti amount under epoxidation conditions) or selectivity in the Catalyst can be installed. If the surface of the inorganic siliceous solid, e.g. in the range of 250 up to 350 m² / g is, the titanium content of the catalyst should be 1 to 5 wt .-%. To the desired Titanium content and the desired activity To achieve, you can also impregnate several times, with or without drying and / or calcining in between.

For the purpose inorganic siliceous solids suitable for the invention are solid materials containing a major portion of silica. Amorphous (i.e., non-crystalline) silicas become particularly prefers. In general, suitable inorganic silicon-containing Solids as well characterized in that it relative to their mass a relative size surface to have. The one used here and usually also in engineering Term to the ratio the surface to express mass is "specific surface". Becomes numeric the specific surface expressed in square meters per gram (m² / g). in the Generally, the inorganic silicon-containing solid has a specific surface of at least 1 m² / g; preferably the average specific surface area is 25 to 1,200 m² / g.

suitable Inorganic siliceous solids include synthetic porous silicas of particles of amorphous silica which have formed flakes or linked together so that they are relatively dense, tight form packed masses. Examples of such materials are silica gel and precipitated Silica. These silica products are porous, i. they have numerous pores, cavities or spaces in theirs Structures.

Other suitable inorganic siliceous solids include synthetic ones Silica powder of particles of amorphous silica, the flakes in packed, easily disassembled and loosely connected aggregates have formed. Exemplary silica powders include fumed Fumed silica caused by the combustion of hydrogen and oxygen was prepared with silicon tetrachloride or tetrafluoride.

synthetic inorganic oxide materials containing a larger proportion of silica, include another class of inorganic siliceous solids. Such materials are known as refractory oxides and include Silica-alumina, silica-magnesia, silica-zirconia, Silica-alumina-boron and silica-alumina-magnesia. Molecular sieves, especially large pores or mesoporous molecular sieves such as MCM-41, MCM-48 and M41S can also be used as inorganic silicon-containing solid can be used.

Especially preferred synthetic inorganic silicon-containing solids are those which consist essentially of pure silica, e.g. Materials of at least 99% silica.

silicon-containing Inorganic solids are known in the art and have been used in the past for the production of titanium-containing heterogeneous catalysts used, such as in US-4,367,342, 4,021,454, 3,829,392 and 3,923,843, EP-A-0 129 814, 0 345 856 and 0 734 764, Japanese application Kokai No. 77-0798 (Chem. Abstracts 98: 135000s), PCT application no. WO 74/23834, German Patent No. 3,205,648 and of Castillo et al. in J. Catalysis 161, pp. 524 to 529 (1996), the teachings of which are hereby incorporated by reference in their entirety become. All silicon-containing materials described in these documents inorganic solids are also suitable for use in the here claimed invention.

It is particularly desirable the inorganic siliceous solid prior to impregnation dry. This drying can e.g. be done by that the inorganic siliceous solid for several hours at a Temperature of 100 to 700 ° C, preferably at least 200 ° C heated. In general, it is not necessary to use temperatures of more than 700 ° C, to achieve a sufficient degree of dryness. A vacuum or a fluent one Electricity from dry gas such as nitrogen can be used to to accelerate the drying process.

It can all conventional Methods are used that allow a porous solid with a soluble impregnating waterproof can be. For example, the titanium halide may be in the hydrocarbon solvent solved and then added to the inorganic siliceous solids or otherwise combined with it. The inorganic ones silicon-containing solids could also the hydrocarbon solution of the titanium halide.

"Wet onset" techniques, which use a minimum amount of solvent to avoid the formation of a slurry, are also suitable. If necessary, the resulting mixture may be aged with stirring or with another mixing technique before further processing. In general, the impregnating solution should be contacted with the inorganic siliceous solids for so long that the solution completely permeates the available pore volume of the solids. The hydrocarbon solvent used for impregnation can then be dried by drying at a moderately elevated temperature (eg 50 to 200 ° C) and / or reduced pressure (eg 1 mm Hg to 100 mm Hg). be removed before calcining. The conditions in the solvent removal step are preferably selected to remove at least 80% and preferably at least 90% of the solvent used for impregnation prior to calcining. The drying step may be preceded by decantation, filtration or centrifugation to remove any excess impregnation solution. The washing of the impregnated silicon-containing solid is not required. Thus, a desirable embodiment of this invention is characterized by the absence of such a washing step.

The impregnated Siliceous solids are burned at elevated temperature calcined. Calcination may be carried out in the presence of oxygen (e.g. from the air) or - preferably - one Inert gas which is substantially free of oxygen, e.g. Nitrogen, argon, neon, helium and the like or a mixture of these gases. The use of a substantially oxygen-free the atmosphere while Calcination generally gives a much more active catalyst than when using an oxygen-containing atmosphere such as air. In one embodiment According to the invention, the calcining is carried out first in a substantially oxygen-free atmosphere, in the later Oxygen is introduced. Preferably, the calcination atmosphere contains less as 10,000 ppm mol Oxygen. Stronger less than 2000 ppm moles are preferred in the calcination atmosphere Oxygen present. Ideally, the oxygen concentration is while Calcining less than 500 ppm. It is recognized, however, that it is difficult in industrial processes on a large scale, a to achieve essentially oxygen-free state. Surprised has been found to be the catalyst with an epoxidation activity that the comparable to virtually calcined catalysts without oxygen is, can be manufactured, even if some oxygen (e.g., up to 25,000 ppm-mole) is present is, as long as reducing gas is present. Carbon monoxide is a particularly effective reducing gas for this purpose. The usage of hydrogen as the reducing gas is generally undesirable since the catalysts thus obtained have a lower activity (Possibly, because water forms under the calcination conditions). The optimal Of course, the amount of the reducing gas fluctuates depending on of different factors like the oxygen concentration in the calcination and the kind of the reducing gas, but reducing gas amounts of 0.1 to 10 mol% in the calcination atmosphere are typically sufficient. In one embodiment According to the invention, the calcining is carried out in an atmosphere which from oxygen, a reducing gas (preferably carbon monoxide) and optionally one or more inert gases (e.g., nitrogen, helium, Argon, carbon dioxide).

Of the Catalyst can during calcination in a fixed bed, wherein a gas stream is passed through the catalyst bed. To the epoxidation activity of the catalyst To improve, it is important that calcining at a temperature of at least 500 ° C carried out becomes. Stronger is preferred the calcination temperature is at least 700 ° C but not more than 1000 ° C. Typically enough Calcination times of about 0.1 to 24 hours.

Of the Catalyst may be after and / or during the calcination process be reacted with water. Such a reaction may, for example by contacting the catalyst with steam at elevated temperature (preferably a temperature of more than 100 ° C, stronger preferably a temperature in the range of 150 to 650 ° C) over about 0.1 to 6 hours are effected. The reaction with water is desirable the amount of residual halide in the catalyst derived from the titanium halide reagent and to increase the hydroxide density of the catalyst.

Of the Catalyst can also be used at elevated temperatures Temperature treated with an organic silylating agent. The epoxide selectivity generally improves with silylation. Preferably silylation after calcination, more preferably after both the calcination and the reaction with water. suitable Silylation process used for the invention can be adapted are in US-A-3,829,392 and 3,923,843 (incorporated herein by reference in their entirety to be incorporated into this application). Suitable silylating agents include organosilanes, organosilylamines and organosilazanes.

dargestellt, in der die R-Gruppen unabhängig voneinander Hydrocarbylgruppen (vorzugsweise C₁-C₄-Alkyl) oder Wasserstoff sind. Besonders bevorzugt für die Verwendung sind die mit Hexaalkyl substituierten Disilazane wie z.B. Hexamethyldisilazan.Organosilanes containing one to three organic substituents can be used, including, for example, chlorotrimethylsilane, dichlorodimethylsilane, nitrotrimethylsilane, chlorotriethylsilane, chlorodimethylphenylsilane, and the like. Preferred organohalosilane silylating agents include tetrasubstituted silanes having from 1 to 3 selected from chlorine, bromine and iodine selected halo substituents, the remaining substituents being methyl, ethyl or a combination thereof. Organodisilazanes are represented by the formula

in which the R groups independently of one another are hydrocarbyl groups (preferably C ₁ -C ₄ -alkyl) or hydrogen. Particularly preferred for use are the hexaalkyl-substituted disilazanes such as hexamethyldisilazane.

The Treatment with the silylating agent may be either in the liquid phase (i.e., when the silylating agent is a liquid, either alone or as a solution in a suitable solvent as hydrocarbon, is applied to the catalyst) or in the vapor phase (i.e., when the silylating agent is in the form of a Gas is brought into contact with the catalyst) take place. The Treatment temperatures are preferably in the range of 80 to 450 ° C, wherein slightly higher Temperatures (e.g., 300 to 425 ° C) in Generally, when the silylating agent is an organohalosilane and organosilazanes have slightly lower temperatures (e.g. 80 to 300 ° C) to be favoured. The silylation can be batchwise, semi-continuous or continuously.

The Duration of time in which the silylating agent with the surface of the Catalyst must react partially depends from the temperature and the medium used. Lower temperatures generally require longer ones Reaction times. Most are enough for 0.1 to 48 hours.

The Amount of silylating agent used can be in a wide range vary. Suitable amounts of the silylating agent can in Range of about 1% by weight (based on the weight of the total Catalyst composition) to about 75% by weight, typically Amounts of 2 to 50 wt .-% are preferred. The silylating agent can be either in a single treatment or a series of Treatments are applied to the catalyst.

The has obtained by this method catalyst composition generally a composition of about 0.1 to 10% by weight (preferably 1 to 5% by weight) of titanium (typically in the form of titanium oxide, preferably in a high positive oxidation state), the remainder being in preferred embodiments the invention predominantly or exclusively made of silica. When the catalyst was silylated, contains it also typically 1 to 4 wt .-% carbon in the form of organic Silyl groups. Relatively small amounts of halide (e.g., up to about 5000 ppm) also be present in the catalyst. A desirable feature of this invention is that they are highly active and selective catalyst compositions can produce, the relatively large Amounts of titanium (e.g., 1 wt% or more). Given the The prior art teaches about the oxygen-containing solvents must be used to minimize titanium agglomeration and catalyst efficiency To maximize this advantage was totally unexpected. The catalyst typically has a porous one Character and a relatively large one surface and may be characterized by being an inorganic Oxygen compound of silicon in chemical combination with an inorganic oxygen compound of titanium (e.g., an oxide or hydroxide).

catalyst compositions can if necessary not disturbing or containing the catalyst accelerating substances, especially those that are opposite are inert to the epoxidation reactants and products. The catalysts can contain minor amounts of accelerators, e.g. alkali metals (such as sodium or potassium) or alkaline earth metals (such as barium, calcium, Magnesium) as oxides or hydroxides. Typically, quantities to alkali metal and / or alkaline earth metal from 0.01 to 5 wt .-% based on the total weight of the catalyst composition.

The Catalyst compositions can be used in any convenient physical form, e.g. when Powder, flakes, granules, globules or pellets. The inorganic silicon-containing solid can before impregnating or Calcinieren in such a form or - alternatively - after the Impregnate and / or calcining from one mold to another physical one Shape are converted. This one uses traditional Techniques such as extrusion, pelletization, milling and the like.

When Olefinic reactants can be obtained in the epoxidation process according to the invention use all hydrocarbons containing at least one olefinic Carbon-carbon double bond and generally 2 to 60 Have carbon atoms, preferably 3 to 10 carbon atoms.

Especially preferred olefinic reactants are the acyclic alkenes with 3 to 10 carbon atoms such as propylene, butene, pentene, hexene, heptene, Octene, nonene, decene and their isomers. Also preferred olefinically unsaturated Compounds containing a hydroxyl or halogen group such as allyl chloride or allyl alcohol are substituted. Preferred organic hydroperoxides are Hydrocarbon hydroperoxides having 3 to 20 carbon atoms. Particularly preferred are secondary and tertiary hydroperoxides with From 3 to 15 carbon atoms, especially secondary alkyl hydroperoxides in which the hydroperoxy group is on a carbon atom, the hanging directly on the aromatic ring, e.g. Ethylbenzene. Other exemplary organic hydroperoxides, for themselves suitable for use include t-butyl hydroperoxide, t-amyl hydroperoxide, Cyclohexyl hydroperoxide and cumene hydroperoxide.

In In such an epoxidation process, the hydroperoxide molar ratio is not particularly critical, but preferred is a molar ratio of 1: 1 to 20: 1 used.

The Epoxidation reaction is in the liquid phase in solvents or thinners performed that at the reaction temperature and the reaction pressure liquid and across from the reactants or the products produced therefrom substantially inen are. In industrial application it is generally most economical, as a solvent to use the hydrocarbon used to make the organic Hydroperoxide reactants was used. For example, when ethylbenzene hydroperoxide The use of ethylbenzene as an epoxidation solvent is used prefers. The reaction is carried out at moderate temperatures and pressures. typically, the organic hydroperoxide is in concentrations of about 1 up to 50% by weight of the epoxidation mixture (including olefin) in front. Suitable reaction temperatures vary between 0 and 200 ° C, amount but preferably 25 to 150 ° C. The reaction is preferably at or above the atmospheric Pressure carried out. The exact pressure is not critical. The reaction mixture may be, for example essentially in a non-gaseous phase or as a two-phase system (Gas and liquid) being held. The catalyst composition is of course Character heterogeneous and therefore lies during the Epoxidationsverfahrens invention as a solid phase. Typical pressures are between 1 atm and 100 atm.

The epoxidation may be carried out using any conventional reactor configuration known in the art for reacting olefin and organic hydroperoxide in the presence of an insoluble catalyst. Both continuous and batch processes can be used. For example, the catalyst can be used in the form of a packed bed or slurry, with provision made to remove the heat generated as a result of the exothermic epoxidation reaction. A catalytic fixed bed reactor which is suitable for the process according to the invention is known in EP 0 323 663 described. When the epoxidation has proceeded to the desired extent, the product mixture is separated and the products (epoxide and alcohol derived from the organic hydroperoxide) recovered by conventional methods such as fractional distillation, selective extraction, filtration and the like. The reaction solvent, the catalyst composition, and all unreacted olefin or organic hydroperoxide are recycled for further use.

Examples

Example 1-A

This Example shows the preparation of a catalyst according to the invention.

A dried sample of Grace V-432 silica (30 g) with a surface of 320 m² / g and a pore volume of 1.1 ml / g was added to a 500 ml 3-neck round bottom flask introduced, which with a condenser, an inlet for inert gas and a gas scrubber, the one watery Containing sodium carbonate solution, equipped was. A solution, the 51 g of heptane and 2.1 ml (3.6 g, 0.019 mol) of titanium tetrachloride was then under a dry inert gas atmosphere in the Piston introduced. The resulting mixture was allowed to stand for two hours using an oil bath until the reflux heated. Then raised the temperature of the oil bath to 150 ° C and drove the solvent by passing an inert gas through the piston. Then you increased the temperature of the oil bath at 200 ° C and kept her at this value for two hours.

The resulting solids were placed in a quartz reactor and heated to 800 ° C under a stream of air. The hydrochloric acid generated during the temperature elevation was washed out using the aqueous sodium carbonate solution. Subsequently, the product was in the presence of the air stream calcined at 800 ° C for two hours. The quartz reactor was cooled to 400 ° C and its contents treated at that temperature using an inert gas as a carrier with steam. A total of 4.5 g (0.25 mol) of water was passed through the catalyst bed. After cooling the quartz reactor to 200 ° C, the catalyst was treated with a flowing inert gas stream containing hexamethyldisilazane in vapor form. In total, 3.0 g of hexamethyldisilazane were passed through the catalyst. Subsequently, the reactor was cooled to ambient temperature under the inert gas stream to give the final catalyst composition.

Example 1-B

The The procedure of Example 1-A was repeated with the difference that the steam treatment at 500 ° C using air as a carrier gas carried out has been.

Example 1-C

The The procedure of Example 1-A was repeated with the difference that the steam treatment at 600 ° C using air as a carrier gas carried out has been.

Example 1-D

The The procedure of Example 1-A was repeated with the difference that the catalyst calcined at 600 ° C. has been.

Example 1-E

The The procedure of Example 1-A was repeated with the difference that the catalyst calcined at 700 ° C. has been.

Example 1-F

The The procedure of Example 1-A was repeated with the difference that the catalyst calcined at 900 ° C. has been.

Example 1-G

The The procedure of Example 1-A was repeated with the difference that the steam treatment was omitted.

Example 1-H

The The procedure of Example 1-A was repeated with the difference that the silylation step has been omitted.

Example 1-I (Comparative Example)

The The procedure of Example 1-A was repeated with the difference that instead of heptane anhydrous isopropanol as a solvent for the impregnation has been used.

Comparative Example 2

This Example shows for comparison purposes the preparation of a catalyst using an alcohol as impregnation solvent and a titanium alkoxide as a titanium source.

A Solution, the 137 g isopropanol and 13.8 g titanium diisopropoxide bis (acetylacetonate) contains is produced.

The solution is added to dried silica in a round bottom flask and mixed thoroughly. (The relative amounts are varied to produce catalysts 2-A and 2-B, which have different titanium contents as seen in Table 1). Subsequently, the solvent is removed with a rotary evaporator with a temperature of 85 ° C. After drying, the material becomes calcined at 800 ° C (ramp rate 5 ° C / min) for six hours in the air.

One Part of the calcined product (78 g) is poured into a tubular glass reactor (1.25 inches outside diameter, 30 inches in length) equipped with a temperature measuring socket, a 500 ml 3-neck round bottom flask, a heating mantle, an in-gas inlet and a water-containing Gas scrubber is equipped. The reactor is placed under a 3-zone furnace under a Nitrogen flow (300 to 600 cc / min) heated. The energy supply is set so that the temperature in each of the three zones between 190 and 200 ° C lies. Hexamethyldisilazane (5.7 g) is added to the flask and this then using the heating mantle until reflux heated. fumes of the hexamethyldisilazane are then removed using an inert gas passed through the catalyst bed. After an hour is the whole Hexamethylsilazane consumed. The bed temperature is at 190 to 200 ° C, while five more For a few hours, a stream of inert gas passed through the reactor bed becomes. Then the apparatus is cooled to ambient temperature under an inert gas stream cooled.

Example 3

Around the performance of those prepared in Example 1 and Comparative Example 2 Catalysts were evaluated as discontinuous epoxidations of 1-octene using ethylbenzene hydroperoxide. To the following procedure was used: a mixture containing 17.0 g of 1-octene, 10 g of a solution of ethylbenzene hydroperoxide in ethylbenzene (obtained by oxidation of ethylbenzene with air) and 1.0 g of nonane (internal standard) in a 4-necked round bottom flask introduced with a capacitor, a thermocouple, a whisk and an opening equipped for taking samples is. The catalyst (0.5 g) is added after heating the mixture to 80 ° C. The mixture is kept at 80 ° C for 30 minutes.

The Results of discontinuous epoxidation using the catalysts prepared as described above summarized in Table 1. The conversion and selectivity are on the basis of the analysis of the feed and the reaction product calculated by gas chromatography. These results show that Catalysts by liquid phase impregnation of silica with a solution of titanium tetrachloride in a hydrocarbon, at similar Titan loading both over higher activity as well as higher selectivity feature as catalysts by liquid phase impregnation of silica with a solution of titanium alkoxide in an alcohol.

Table 1

Example 4-A

A dried sample of silica (30 g) was placed in a 500 ml 3-neck round bottom flask equipped with a condenser, an inert gas inlet and a gas scrubber containing sodium carbonate solution. Then, under a dry inert gas atmosphere, a solution containing 51 g of heptane and 2.1 ml (3.6 g, 0.019 mol) of TiCl _{4 was} added to the flask. After thoroughly mixing the flask contents under a dry inert gas atmosphere, the temperature of the oil bath was raised to 150 ° C and the solvent was driven off by allowing inert gas to flow through the system. Then, the temperature of the oil bath was further raised to 200 ° C and kept at that value for 2 hours. The dried impregnated silica was then placed in a quartz reactor and heated to 850 ° C with an air stream passing through the reactor. The hydrochloric acid generated during the temperature increase was washed out with the sodium carbonate solution. After heating at 850 ° C for half an hour, the reactor was cooled to 400 ° C and the catalyst treated using an inert gas as a carrier with water vapor. A total of 4.5 g (0.25 mol) of water was passed through the catalyst bed. Subsequently, the reactor was cooled to 200 ° C and the catalyst then treated with an inert gas stream containing hexamethyldisilazane (HMDS) in vapor form. A total of 3.0 grams of HMDS was passed through the catalyst bed. Subsequently, the reactor was cooled under an inert gas stream.

Example 4-B

example 4-A was repeated with the difference that calcination at 850 ° C 30 Minutes using a helium stream.

Example 4-C

example 4-A was repeated with the difference that calcination was taking place Use of a helium stream was carried out and the temperature while of calcining during increased to 900 ° C over a period of 1.5 hours and then lowered to 600 ° C has been.

Example 4-D

example 4-A was repeated except that the hexane was used as the impregnation solvent has been.

Example 5

The catalytic performance of those prepared in Examples 4-A to 4-D Materials were compared. This was done using the same procedure a discontinuous epoxidation as described in Example 3. The results summarized in the following Table 2 confirm that the activity becomes significantly better when under an inert gas atmosphere (Examples 4-B to 4-D) instead of an oxygen-containing atmosphere (Example 4-A) is calcined. It is not a detrimental effect on the epoxide to observe.

Table 2

Example 6

The performance of Catalyst 4-A was tested in a fixed bed propylene epoxidation reaction. The reactor was charged with 25 g of catalyst. Then, at a space velocity of the liquid of 8 h ^-1 and a pressure of 885 psig, a reaction mixture of 12 moles of propylene per mole of ethylbenzene hydroperoxide in ethylbenzene was fed. The concentration of ethylbenzene hydroperoxide in ethylbenzene was 35 Wt .-%. After 266 hours, the average bed temperature was 78 ° C and the ethylbenzene hydroperoxide conversion and propylene oxide selectivity were 98 and 99%, respectively.

Example 7

The Performance of the catalyst 4-C was under the same conditions tested as in Example 6. After 261 hours, the average was Bed temperature 73 ° C and ethylbenzene hydroperoxide conversion and propylene oxide selectivity 99 and 98%.

Example 8-A

A dried sample of silica (103 g) was added to a 500 ml 3-neck round bottom flask inserted, containing an inert gas inlet, a gas outlet and an aqueous sodium hydroxide solution gas scrubber equipped was. A solution, the 143 g of n-heptane (99+%, <50 ppm water) and 7.4 ml of titanium (IV) tetrachloride (12.8 g, 0.067 mol) was added to the flask under a dry inert gas atmosphere. The mixture was thoroughly mixed by vortexing. The solvent using a rotary evaporator at 80 ° C and 5 to 10 mbar pressure removed.

One Part of the thus obtained impregnated silica was in a tubular quartz reactor (1 inch outside diameter, 16 inches long) introduced, the with a temperature gauge, a 500 ml 3-neck round bottom flask, a heating jacket, an inert gas inlet and a (aqueous Sodium hydroxide containing) scrubber was equipped. The bed of impregnated Silica was bubbled under a stream of dry nitrogen (99.999 % Purity; 400 cc / min). After the bed temperature had been at 850 ° C for 30 minutes, the energy supply became switched off to the furnace and the catalyst bed cooled to 400 ° C.

Water (5.0 g) was then added to the 3-neck round bottom flask and the contents heated to reflux with a heating mantle while maintaining the N ₂ flow at 400 cc / min. The water was distilled through the catalyst bed over a period of 30 minutes using a heat gun to heat the round bottom flask to ensure that all of the residual water had been driven out of the flask and through the reactor bed. After keeping the bed at 400 ° C for an additional two hours, the tube reactor was allowed to cool to room temperature.

Of the thereby obtained steam-treated catalyst (35 g) was combined with 70 g of heptane (<50 ppm water) and 4.4 g of hexamethylsilazane in a 500 ml 3-neck round bottom flask brought in. The flask was equipped with a condenser, a thermometer and a gas inlet. Subsequently was using a 115 ° C oil bath an inert atmosphere until the reflux (98 ° C) and heated 4 hours at reflux held. After cooling under an inert gas atmosphere the catalyst composition was collected by filtration, washed with 100 ml of heptane and then under an inert gas at 180 to 200 ° C dried for two hours.

Example 8-B

With the same procedure as in Example 8-A became a catalyst composition prepared with the difference that the calcination and steaming steps not under a stream of nitrogen, but under a stream of air carried out were.

Example 8-C

With the same procedure as in Example 8-A became a catalyst composition prepared with the difference that the calcination and steaming steps using nitrogen containing 2000 ppm-mole oxygen, carried out were.

Example 8-D

With the same procedure as in Example 8-A became a catalyst composition prepared with the difference that the calcination and steaming steps using nitrogen containing 4 mol% carbon dioxide, carried out were.

Example 8-E

With the same procedure as in Example 8-A became a catalyst composition prepared with the difference that the calcination and steaming steps using nitrogen, the 6000 ppm-mole of oxygen and 4 mol% carbon monoxide contained were performed.

Example 8-F

With the same procedure as in Example 8-A became a catalyst composition prepared with the difference that the calcination and steaming steps using nitrogen containing 1 mol% hydrogen, carried out were.

Example 8-G

With the same procedure as in Example 8-A became a catalyst composition prepared with the difference that the calcination and steaming steps using nitrogen, the 4 mol% hydrogen and 0.5 Mol% oxygen, were carried out.

Example 8-H

With the same procedure as in Example 8-A became a catalyst composition prepared with the difference that the calcination at 500 ° C for 30 minutes long performed has been.

Example 8-I

With the same procedure as in Example 8-A became a catalyst composition prepared with the difference that the calcination at 400 ° C for 30 minutes long performed has been.

Example 8-J

With the same procedure as in Example 8-A became a catalyst composition prepared with the difference that the calcination at 300 ° C for 30 minutes long performed has been.

Example 9

The catalyst compositions prepared in Examples 8-A to 8-J were in a discontinuous epoxidation of 1-octene with tested following procedure. It is prepared by mixing 170 g 1-octene, 100 g ethylbenzene hydroperoxide solution in ethylbenzene (prepared by oxidation of ethylbenzene) and 10 g of nonane (internal standard) a feed solution ago. A 100 ml 3-neck round bottom flask, the one with a capacitor, a thermocouple, a stir bar and an opening equipped for taking samples is immersed under an inert atmosphere in an oil bath of 60 ° C and then with 28 g the above feed solution fed. The feed solution in the flask is at 58 to 59 ° C heated while with the stir bar is stirred at a speed of 700 rpm. Then 0.5 g the catalyst composition to be tested in the Piston introduced. The temperature of the reaction mixture is in the first ten minutes at one-minute intervals and then measured at 5 minute intervals. In general, that varies Temperature of the reaction mixture between 60 and 63 ° C. A 3 ml sample of the reaction mixture becomes 30 minutes after addition of the catalyst composition taken. Both the feed solution and the product samples are analyzed by gas chromatography to determine the concentrations of hydroperoxide and epoxyoctane. Then the transformation and the epoxide calculated based on the consumed hydroperoxide.

The epoxidation results obtained are shown in Table 3. As can be seen, the composition of the atmosphere under which it was calcined had a significant effect on the catalyst activity. Even the small amount of oxygen during calcination in Example. 8 leads to the production of a less active catalyst (comparisons run 9-C with run 9-A). However, the adverse effect of small amounts of oxygen can be avoided if there is also a reducing gas such as carbon monoxide during calcination (see Run 9-E). The calcination temperature also proved to be an important factor influencing the activity of the catalyst. When this temperature was lowered from 850 to 500 ° C, the conversion of ethylbenzene hydroperoxide dropped by more than half (compare runs 9-A and 9-H). Further losses of catalyst activity were observed when the Calcination temperature below 500 ° C dropped.

Table 3

Claims (34)

Completely bring into contact epoxidation an organic hydroperoxide having an olefin in the. presence a catalyst composition obtained by a process comprising the steps of: (a) impregnate of an inorganic siliciumhaitigen solid with a solution of a Titanium halide in a non-oxidized hydrocarbon solvent; and (b) calcining the impregnated silicon-containing solid to form the catalyst composition; is obtained, wherein the process by the substantial exclusion of water until at least Step (a) is completed. The epoxidation process of claim 1, wherein the Titanium halide is titanium tetrachloride. An epoxidation process according to claim 1, wherein said impregnation step (1) is through a solution of the titanium halide in the non-oxidized hydrocarbon solvent with the to combine inorganic siliceous solid and then the Kohlenwasserstofffösungsmittel to remove. The epoxidation process of claim 1, wherein the inorganic siliceous solid is silica. The epoxidation process of claim 1, wherein the unoxidized hydrocarbon solvent is selected from the group consisting of C ₅ -C ₁₂ aliphatic hydrocarbons, C ₆ -C ₁₂ aromatic hydrocarbons, C ₁ -C ₁₀ hydrogenated aliphatic hydrocarbons, C ₆ -C ₁₀ halogenated aromatic hydrocarbons, and whose mixtures are selected. The epoxidation process of claim 1, wherein the Method for obtaining the catalyst composition an additional Step after step (b) of heating the catalyst composition in the presence of water. The epoxidation process of claim 1, wherein water is substantially excluded until step (b) is completed. The epoxidation process of claim 1, wherein the Method for obtaining the catalyst composition an additional Step after step (b) of treating the catalyst composition with a silylation agent. The epoxidation process of claim 1, wherein the method of obtaining the catalyst composition comprises additional steps after step (b) of heating the catalyst composition in the Angew water and treating the catalyst composition with a silylating agent. The epoxidation process of claim 1, wherein calcination step (B) is carried out at a temperature of at least 500 ° C. The epoxidation process of claim 1, wherein the organic hydroperoxide is ethylbenzene hydroperoxide. The epoxidation process of claim 1, wherein the olefin is a C ₃ -C ₁₀ acyclic alkene. The epoxidation process of claim 1, wherein step (B) is carried out in a substantially oxygen-free atmosphere. The epoxidation process of claim 1, wherein step (B) is carried out in an atmosphere consisting of oxygen and a reducing gas. An epoxidation process comprising contacting ethylbenzene hydroperoxide with propylene in the presence of a catalytically effective amount of a catalyst composition obtained by a process comprising the steps of: (a) forming a mixture through a solution of titanium tetrachloride in a hydrocarbon solvent selected from the group consisting of C; C ₅ -C ₁₂ aliphatic hydrocarbons, C ₆ -C ₁₂ aromatic hydrocarbons, C ₁ -C ₁₀ halogenated aliphatic hydrocarbons, C ₆ -C ₁₀ halogenated aromatic hydrocarbons and mixtures thereof, to be combined with silica; (b) removing the hydrocarbon solvent from the mixture to produce an impregnated silica; (c) calcining the impregnated silica at a temperature of 700 ° C to 1000 ° C to form a calcined catalyst precursor; (d) heating the calcined catalyst precursor in the presence of water; and (e) treating the calcined catalyst precursor with a silylation agent; wherein the process is completed by the substantial exclusion of water to step (c). The epoxidation process of claim 15, wherein step (C) is carried out in a substantially oxygen-free atmosphere. The epoxidation process of claim 15, wherein step (C) is carried out in an atmosphere consisting of oxygen and a reducing gas. The epoxidation process of claim 15, wherein said Silylation agent from the group consisting of organosilanes, organosilylamines, Organosilazanes and mixtures thereof is selected. The epoxidation process of claim 15, wherein the Catalyst composition has a Ti content of 1 to 5 weight percent Has. The epoxidation process of claim 15, wherein said Method of obtaining the catalyst composition the additional Step before step (a) of drying the silica. Process for preparing a catalyst composition comprising the steps of: (a) impregnating an inorganic one siliceous solid with a solution of a titanium halide in a non-oxidized hydrocarbon solvent; (b) calcining of the impregnated silicon-containing solid around a calcined catalyst precursor form; and at least one of the steps (c) or (d); (C) Heating the calcined catalyst precursor in the presence of Water; or (d) treating the calcined catalyst precursor with a silylation agent; the process being characterized by the essential exclusion from water until at least step (a) is completed becomes. The method of claim 21, wherein step (b) in a substantially oxygen-free atmosphere is performed. The method of claim 21, wherein the titanium halide Titanium tetrachloride is. The method of claim 21, wherein impregnation step (a) by combining a solution of the titanium halide in the non-oxidized hydrocarbon solvent with the inorganic silicon-containing solid and then. Removing the hydrocarbon solvent, carried out becomes. The method of claim 21, wherein the inorganic silicon-containing solid is silica. The method of claim 21, wherein both steps (c) and (d) executed become. The method of claim 21, wherein step (b) in the essential absence of water is carried out. The method of claim 21, wherein step (b) in an atmosphere consisting of oxygen and a reducing gas is performed. The method of claim 21, wherein step (b) is at a temperature of at least 500 ° C is performed. A process for preparing a catalyst composition comprising the steps of (a) forming a mixture by a solution of titanium tetrachloride in a hydrocarbon solvent selected from the group consisting of C ₅ -C ₁₆ aliphatic hydrocarbons, C ₆ -C ₁₂ aromatic hydrocarbons, C ₁ -C ₁₀ halogenated aliphatic hydrocarbons, C ₆ -C ₁₀ halogenated aromatic hydrocarbons and mixtures thereof, to be combined with silica; (b) removing the hydrocarbon solvent from the mixture to produce an impregnated silica; (c) calcining the impregnated silica at a temperature of 700 ° C to 1000 ° C to form a calcined catalyst precursor; (d) heating the calcined catalyst precursor in the presence of water; and (e) treating the calcined catalyst precursor with a silylating agent; the process being characterized by the substantial exclusion of water until at least step (a) is completed. The method of claim 30, wherein step (c) in a substantially oxygen-free atmosphere is performed. The method of claim 30, wherein step (c) in an atmosphere consisting of oxygen and a reducing gas is performed. The method of claim 30, wherein the reducing gas Carbon monoxide is. The method of claim 30, comprising an additional Step before step (a) of drying the silica.